Sustained releasable parenteral pharmaceutical preparations and method of producing the same

ABSTRACT

A parenteral pharmaceutical preparation comprises a matrix containing a physiologically active peptide or protein and a polyglycerol diester of a saturated fatty acid, and the matrix is in a solid form at room temperature. The molecular weight of the physiologically active peptide or protein is 2,000 dalton or more. The saturated fatty acid includes fatty acids having about 16 to 30 carbon atoms such as palmitic acid, stearic acid, etc. The matrix may be in a pillar or granular form. The parenteral pharmaceutical preparation can be used as an injectable solid administered subcutaneously or intramuscularly (for example, a pellet or tablet for implantation), a suppository or the like, and can release the physiologically active peptide or protein sustainedly for a prolonged period of one week or more.

FIELD OF THE INVENTION

The present invention relates to a sustained releasable parenteralpreparation useful for sustained or prolonged release of aphysiologically active peptide or protein, and a method of producing thesame.

BACKGROUND OF THE INVENTION

For administration of a therapeutic agent, oral administration isgenerally employed. Oral administration of a physiologically activepeptide or protein, however, causes hydrolysis of the peptide or proteinby a digestive enzyme to decrease disadvantageously the absorbabilityfrom the digestive tract. Accordingly, such physiologically activepeptide or protein is usually administered by repetition ofintramuscular or subcutaneous injections or by intravenous dripinfusion. These methods, however, are not preferable in a chronicadministration, although they are acceptable in a case where therepetition of the injection is extremely limited. By way ofillustrating, for the therapy of viral hepatitis type C, interferon-α iscontinuously administered daily throughout 4 weeks or more (see "Journalof Clinical and Experimental Medicine (IGAKU NO AYUMI)", 161, 5, 359-363(1992)). In such chronic or frequent administration, however, thepatient is obliged to be restrained to a great extent. Therefore,development of an effective and economic administration system for suchphysiologically active peptide or protein has been demanded.

Japanese Patent Application Laid-open No. 2930/1988 (JP-A-63-2930)discloses a system where a polypeptide is dispersed in a polylactide.Japanese Patent Publication No. 502117/1988 (JP-B-63-502117) andJapanese Patent Application Laid-open No. 234820/1992 (JP-A-4-234820)disclose pharmaceutical preparations using a liposome, and JapanesePatent Publication No. 502574/1991 (JP-B-3-502574) proposes apharmaceutical preparation where a liposome containing a physiologicallyactive polypeptide is dispersed in a gel.

When these pharmaceutical preparations are administered, however, thedrugs are unexpectedly released to a large extent in the initial stageof administration. Thus the drug concentration in blood is increased andthe releasing rate of the drug can not be maintained in a certain range.Furthermore, since an organic solvent is used in the manufacture of thepreparation, the polypeptide is denaturated to decrease thephysiological activity.

Japanese Patent Application Laid-open No. 2930/1988 (JP-A-63-2930)discloses a sustained releasable system for a physiologically activepolypeptide, which comprises an atherocollagen-matrix and thephysiologically active polypeptide dispersed in the matrix. Theatherocollagen used as a base is, however, derived from a foreign ordifferent animal from human being, and it may probably showantigenicity.

Japanese Patent Application Laid-open No. 22012/1988 (JP-A-63-22012)discloses a system prepared by dispersing a physiologically activepolypeptide in a water-insoluble matrix and compression-molding thedispersion, as a sustained releasable pharmaceutical preparation forparenteral administration of the polypeptide. The pharmaceuticalpreparation controls the release of the physiologically activepolypeptide by utilizing erosion of the matrix in vivo. Therefore, thepolypeptide may be enzymatically degraded or decomposed so as to lowerthe biological availability.

Japanese Patent Application Laid-open No. 85328/1986 (JP-A-61-85328)discloses a pharmaceutical preparation which comprises a composition ofa physiologically active polypeptide and a polyglycerol fatty acidester, wherein the polyglycerol fatty acid ester is dispersed in water.The pharmaceutical preparation is, however, restricted with regard to adosage form since it is a solution. Furthermore, since the polyglycerolfatty acid ester is utilized to promote the percutaneous absorption ofthe physiologically active polypeptide, and the drug can hardly bereleased for a longer period of time, e.g. for 24 hours or more.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide asustained releasable parenteral pharmaceutical preparation in whichhydrolysis of a physiologically active peptide or protein can besuppressed, the decrease of their activity can be avoided and asustained release of the peptide or protein can be maintained for aprolonged period.

It is another object of the present invention to provide a sustainedreleasable parenteral pharmaceutical preparation in which a greatrelease of a physiologically active peptide or protein in an early stageof the administration is suppressed and the peptide or protein can bereleased for a longer period.

It is yet another object of the invention to provide a sustainedreleasable parenteral pharmaceutical preparation in which aphysiologically active peptide or protein can be released sustainedlyfor a prolonged period, wherein denaturation of the higher-dimensionalstructure is suppressed and decrease of the activity of thephysiologically active peptide or protein is inhibited.

It is a further object of the invention to provide a sustainedreleasable parenteral pharmaceutical preparation which does not containany material causing antigenicity and can release a physiologicallyactive peptide or protein for one week or more.

A yet further object of the present invention is to provide a method ofproducing a pharmaceutical preparation, by which the pharmaceuticalpreparation having such excellent characteristics as above can beproduced in a simple and easy manner.

After intensive investigation and research to accomplish the aboveobjects, the inventors of the present invention found that apharmaceutical preparation obtainable by use of specific polyglycerolfatty acid esters selected from numerous polyglycerol fatty acid estersin combination with a physiologically active polypeptide or protein canremarkably improve the sustained release of the physiologically activepeptide or protein, and can release the physiologically active peptideor protein sustainedly for a prolonged period. The present invention hasbeen accomplished based on these findings.

Thus, the sustained releasable parenteral pharmaceutical preparation ofthe present invention comprises a matrix comprising a physiologicallyactive peptide or protein (hereinafter, as far as not particularlymentioned, referred to simply as the physiologically active polypeptide)and a polyglycerol diester of a saturated fatty acid. The averagemolecular weight of the physiologically active polypeptide mayfrequently be 2,000 dalton or more, and the diester may be, in manycases, a diester formed with a polyglycerol having an averagepolymerization degree of about 4 and a saturated fatty acid having 16 to30 carbon atoms. The matrix may be in a pillar, granular or other form.The matrix may be an injectable solid for implantation.

The sustained releasable pharmaceutical preparation may be prepared bymixing a physiologically active peptide or protein with a molten orsoftened polyglycerol diester of a saturated fatty acid and molding themolten mixture.

DETAILED DESCRIPTION OF THE INVENTION

In this specification, the term "polyglycerol having an averagepolymerization degree of 4" means a polymerization degree ofpolyglycerol as a main compound which is estimated by the terminalanalysis of hydroxyl value, and includes tetraglycerol, as well as amixture of tetraglycerol as a main component and an unavoidable glycerolor glycerol polymer (for example, diglycerol, triglycerol,pentaglycerol, etc.). Therefore, the average polymerization degree ofthe polyglycerol may be about 3.7 to 4.3.

The term "diester" means the average value of the ester bonds of a maincompound which is estimated from the ester value of the polyglycerolfatty acid ester, and includes not only a diester but also a mixturecomprising a diester as a main component, and a monoester, a triesterwhich may be coexistent or contaminative unavoidably. Thus, the averagevalue of the ester bond in the diester may be about 1.7 to 2.3.

In cases where the matrix or the polyglycerol diester of a fatty acid isnot a single compound but a mixture, the substance does not show adistinct melting point but softens at a specific temperature. The term"melting point" as used in this specification includes, within themeaning thereof, the softening point of such a mixture as well.

As the physiologically active polypeptide in the present invention,various peptides and proteins having physiological activities can beused. The average molecular weight of the physiologically activepolypeptide is, for example, about 2,000 dalton or more, preferablyabout 5,000 to 1,000,000 dalton, more preferably about 10,000 to 500,000dalton and particularly about 10,000 to 100,000 dalton. Preferredphysiologically active polypeptide includes molecules classified intoproteins which is expressed as having a higher-dimensional structure inthe field of biochemistry.

The physiologically active polypeptide includes classificatorily, forexample, proteins, enzymes, nucleoproteins, glycoproteins, lipoproteins,polypeptides having a hormone-like activity, agonists of thesemolecules, synthetic analogues including antagonists and so on.

The present invention may be applied to a variety of physiologicallyactive polypeptides and the species thereof is not criticallyrestricted. As examples of the physiologically active polypeptides,there may be mentioned immune-controlling factors, lymphokines,monokines, cytokines, enzymes, antibodies, growth stimulating factors,growth suppressing factors, hormones, vaccines (including antigens ofviruses, bacteria, parasites and rickettsiae), blood coagulatingfactors, and various precursor proteins thereof, mutant proteins, andother substances analogous thereto.

To be specified, the physiologically active polypeptide includes, forexample, the following physiologically active high molecular compounds,mutant proteins and analogues thereto.

(1) Interferons (α-, β-, γ-, etc.), interleukins (IL-1, IL-2, IL-3,IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11), antiallergic factors,suppressor factors, cytotoxic glycoproteins, immuno-cytotoxic factors,immuno-toxins, lymphotoxins, tumor necrosis factors (TNF-α, TNF-β, orthe like), cachectin, oncostatins, transforming growth factors (TGF-α,TGF-β and so on), hemopoietic factors (for example, erythropoietin),granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophagecolony stimulating factor (GM-CSF), macrophage-colony stimulating factor(M-CSF), macrophage peptides, B-cell factors (e.g. B-cell growth factor,etc.), T-cell factors and so on.

(2) Growth factors, for instance, nerve growth factor (NGF), nervetrophic factor (NTF), polypeptides having actions on cranial nervecells, epitheliocyte growth factor (EGF), insulin-like growth factor(IGF), growth hormone (GH), fibroblast growth factor (FGF), osteogengrowth factor, atrical natriuretic factor (ANP), cartilage inducingfactor and others. The physiologically active polypeptide belonging tothis category further includes, for instance, parathyroid hormone (PTH),endoserine and the like.

(3) Physiologically active polypeptides having a platelet growing actionsuch as platelet-derived growth factor (PDGF), etc.

(4) Physiologically active polypeptides having an enzymatic actionincluding, for instance, factor VIII, factor IX, fibrinolysis factor,tissue plasminogen activator (TPA), urokinase, prourokinase,streptokinase, lipocortin, macrocortin, protein C, C-reactive protein,renin-inhibitor, metalloproteases, tissue inhibitor of metalloprotease(TIMP), superoxide dismutase (SOD) and so on.

(5) Physiologically active polypeptides having a hormone-like actionsuch as insulin, secretin, growth hormone releasing factor (GRF),glucagon, gastrins, prolactin, adrenocorticotropic hormone (ACTH),thyroid-stimulating hormone (TSH), luteinizing hormone (LH),follicle-stimulating hormone (FSH), cholecystokinin, human chorionicgonadotropin (HCG), leukokinin, thymocin, motilin, kallikrein, etc.

(6) Physiologically active polypeptides acting as a vaccine antigenincluding antigens such as HTLV-I, HTLV-II, AIDS virus group (e.g.HTLV-III/LAV/HIV and HIV-2, etc.), cytomegalovirus, hepatitis A virus,hepatitis B virus, hepatitis C virus, herpes simplex-I virus, herpessimplex-II virus, malaria, larvate rabies retrovirus, infectiousgastroenteritis virus, parainfluenza virus, influenza virus, rotavirusgroup, respiratory syncytial virus, varicella-zoster virus, Epstein-Barrvirus, pertussis; and Gram negative bacteria such as Pseudomonas,endotoxins, tetanus toxin, and others. Such physiologically activepolypeptide may be administered singly, or bonded with a hapten, or incombination with an adjuvant.

These physiologically active polypeptides may be naturally-occurring, orbe prepared by genetic recombination. The physiologically activepolypeptide may have a glycosyl chain, and the structure of glycosylchain may be different. Further, examples of the physiologically activepolypeptide include mutants, derivatives, relatives or analogues, oractive fragments of the peptides and proteins mentioned above.

The physiologically active polypeptide may be used singly or incombination. A substance which can activate the physiologically activepolypeptide and/or other ingredient having arithmetic or synergisticeffects with the substance can advantageously be employed in combinationwith the physiologically active polypeptide. For instance, interferon-αcan be used in combination with the activating substance or ingredientsuch as interleukins, lentinan, minophagen or the like. The activatingsubstance or ingredient may be used singly or in combination, with thephysiologically active polypeptide.

The present invention is characterized in that the physiologicallyactive polypeptide is sustainedly releasable for a prolonged period bymeans of combining specific polyglycerol fatty acid esters among a greatnumber of polyglycerol fatty acid esters.

In the polyglycerol fatty acid ester, the term "polyglycerol" means "apolyhydric alcohol having in each molecule thereof n (when cyclic) ton+2 (when straight-chained or branched) hydroxyl groups, and n-1 (whenstraight-chained or branched) to n (when cyclic) ether bonds"["Polyglycerol Ester" edited and published by Sakamoto Yakuhin KogyoCo., Ltd., Japan; pp 12, (May 2, 1986)]. Polyglycerol can be obtained bydehydrating condensation of glycerol, or recovery from residue ofglycerol distillation.

As the component used in combination with the physiologically activepolypeptide, a polyglycerol diester of a saturated fatty acid isemployed in the present invention. When the fatty acid is an unsaturatedfatty acid, the physiologically active polypeptide may be released in anearly stage, and the sustained release may be extremely decreased orreduced. Furthermore, even when the compound is an ester formed with apolyglycerol and a saturated fatty acid, a monoester, a triester, atetraester, a pentaester, or the like may harm or reduce the sustainedrelease of the physiologically active polypeptide remarkably.

Examples of the saturated fatty acid include a saturated fatty acidhaving 16 to 30 carbon atoms such as palmitic acid, datulic acid,stearic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid,montanic acid, melissic acid and so on. Preferred examples of thesaturated fatty acid include a fatty acid having 16 to 22 carbon atoms(for example, palmitic acid, stearic acid, behenic acid, etc.),particularly palmitic acid, stearic acid and the like.

The diesters of these saturated fatty acids may be diester formed with asingle fatty acid or with a mixture of two or more of fatty acids.

The polymerization degree of the polyglycerol is not particularlylimited to a specific value which does not adversely affect on thesustained releasing properties, and is selected from the range dependingon the species of the fatty acid.

Preferred polyglycerol has an average polymerization degree of about 3to 5, particularly 4. Where the average polymerization degree is lessthan 3 or more than 5, depending on the species of the saturated fattyacid, the physiologically active polypeptide may be apt to be releasedor liberated readily, and, in some cases, may hardly be imparted withhigh sustained releasing properties. Therefore, a polyglycerol having anaverage polymerization degree of 4 is advisably employed.

The melting point of the polyglycerol diester of the saturated fattyacid is for example about 40° to 60° C., preferably about 42° to 58° C.and more preferably about 45° to 55° C.

The preferred polyglycerol diester of the saturated fatty acid is formedwith a polyglycerol having an average polymerization degree of 4 and asaturated fatty acid having 16 to 22 carbon atoms.

Examples of the polyglycerol diester having of the saturated fatty acidincludes triglycerol diesters such as triglycerol dipalmitate,triglycerol distearate and triglycerol dibehenate; tetraglyceroldiesters such as tetraglycerol dipalmitate, tetraglycerol didatulate,tetraglycerol distearate, tetraglycerol diarachate, tetraglyceroldibehenate, tetraglycerol dilignocerate, tetraglycerol dicerotate,tetraglycerol dimontante, tetraglycerol dimelissate, tetraglycerolmonopalmitate monostearate, tetraglycerol monopalmitate monobehenate andtetraglycerol monostearate monobehenate; pentaglycerol diesters such aspentaglycerol dipalmitate, pentaglycerol distearate, pentaglyceroldibehenate and the like. Preferred examples of the diester includetetraglycerol diesters such as tetraglycerol dipalmitate, tetraglyceroldistearate, tetraglycerol dibehenate and others. These diesters can beemployed independently or in combination.

The polyglycerol diester is usable for an emulsifier as a food additive,and the safety in vivo has already been confirmed. Further, the diestermay finally be absorbed in vivo and moreover presents no antigenicity.

Matrixes comprising a polyglycerol higher fatty acid ester and a peptideor protein are disclosed in Japanese Patent Application Laid-open No.223533/1990 (JP-A-2-223533), EP-A 443572, Japanese Patent ApplicationLaid-open Nos. 237/1993 (JP-A-5-237) and 132416/1993 (JP-A-5-132416).However, these prior literatures do not disclose that a matrixcomprising a combination of a polyglycerol diester of the saturatedfatty acid and a physiologically active polypeptide can release thephysiologically active polypeptide for an extremely prolonged timeperiod.

The pharmaceutical preparation of the present invention is composed of amatrix comprising the physiologically active polypeptide and thediester. Usually, preferred preparation is formed with a matrix whereinthe physiologically active polypeptide is dispersed in the diester. Thematrix is preferably in a solid form at room temperature or ambienttemperature (5° C. to 35° C.), and, usually, the physiologically activepolypeptide is homogeneously dispersed in the diester. When thephysiologically active polypeptide is dissolved in the molten diester inthe manufacturing procedure, it is preferable to mix homogeneously togive a pharmaceutical preparation where the polypeptide is dispersed ina solid form at room temperature. Such pharmaceutical preparation ischaracterized by suppressing the release of the physiologically activepolypeptide in the early stage of the administration to a great extent,and sustainedly or continuously releasing of the peptide for a prolongedtime period with maintaining the higher-dimensional structure thereof.

The ratio of the physiologically active polypeptide relative to thediester can be selected from a wide range, and the proportion of thephysiologically active polypeptide in the matrix composed of the twocomponents is, for instance, about 0.0001 to 50% by weight, preferablyabout 0.001 to 20% by weight and more preferably about 0.001 to 10% byweight, and the residue is formed with the diester.

The matrix may be added, if required, with an ingredient commonly usedin the field of solid pharmaceutical preparations such as an excipient,a binder and a disintegration agent, as well as various additives suchas a stabilizing agent, a preservative and the like. Examples of thestabilizing agent include gelatin, albumin, globulin, protamine,trehalose, D-glucose, dextran and others. As the preservative, there maybe mentioned, for instance, paraoxybenzoic acid esters (for example,methylparaben, propylparaben, etc.), benzyl alcohol, chlorobutanol,thimerosal and so on.

The sustained releasable parenteral pharmaceutical preparation may be inany form so far as to be administered parenterally or non-orally, andis, usually, formed with a matrix in such a dosage form that will notgive a patient an excessive pain or suffering, for example, a small orcompact matrix. A characteristic of the present invention is that evensuch small or compact matrix as to be administrable by means of, forinstance, a needle for injection, the physiologically active polypeptidecan be released sustainedly for a prolonged period. By way ofillustration, non-oral administration of the present pharmaceuticalpreparation can prolong the period of the physiologically activepolypeptide in blood, for instance, 7 days or more, in comparison with asingle or separate administration of the physiologically activepolypeptide. Thus, the dosage time of the preparation and pain orsuffering given to the patient can extremely be reduced.

The pharmaceutical preparation may be utilized as, for instance, aninjectable solid which is administrable subcutaneously orintramuscularly (e.g. a pellet or implant, etc.), or a transmucosallyabsorbable composition such as a suppository. The shape or form of thepreparation can be selected from a range depending on the dosage form,and may, for instance, be in a powdery or granular form as a powder, agranule or a pill; in a flat, ellipse, rod or pillar form as aninjectable pellet or tablet for implantation; or in a spherical or ovalform as a suppository. When used as an injection, the preparation mayfrequently be in a pillar or powdery form. Preferred form of thepharmaceutical preparation includes, for instance, pillar form such ascylindrical or columnar form and granular form such as spherical form.

The size of the parenteral or non-oral pharmaceutical preparation of thepresent invention may also be selected according to the dosage form, asfar as it will not pain a patient to an excessive extent. For aninjection, when the preparation is a pillar-formed matrix, the size isfor example about 3 mm or less in diameter and about 30 mm or less inlength, preferably about 1 mm or less in diameter and about 20 mm orless in length which can be administered by using a needle of 11 G orless, more preferably about 0.1 to 1 mm in diameter and about 1 to 20 mmin length, and practically preferred is in a cylindrical or columnarform. The grain or particle size of an injectable granular matrix is, inmaximum diameter, about 1 mm or less, preferably about 150 μm or lessand more preferably about 1 to 100 μm. The weight of the matrix may bechosen depending on the form or shape of th pharmaceutical preparation,and is usually, for example, about 40 mg or less and preferably about 1to 25 mg for an injection.

The pharmaceutical preparation of the present invention can be preparedby various methods, and the preferred is such that using no organicsolvent which denatures the polypeptide. As such a method, there may bementioned, for instance, a process which comprises mixing aphysiologically active polypeptide to a molten or softened polyglyceroldiester of the saturated fatty acid, and molding the resultant moltenmixture into a preparation. Although the physiologically activepolypeptide is thermodynamically unstable in an aqueous solution, it isunexpectedly stable in a solid form such as a freeze-dried powder.Therefore, the physiologically active polypeptide in a solid powdery orgranular form such as a dried powder is preferably used for homogeneousmixing.

In the molding, any molding method can be employed according to the formor shape of the pharmaceutical preparation. For instance, an injectioncan be prepared by sucking up the molten mixture into a syringe with aneedle and extruding the charged from the needle to give a pillarproduct or by dropping the molten mixture onto a rotary plate or diskand centrifuging or tumbling the droplets to obtain a spherical product.Further, a fine particulate pharmaceutical preparation can be producedby atomizing or spraying the molten mixture and chilling the powderyproduct, or by subjecting the shaped product such as a pellet to apulverizing means such as a jet mill to obtain a fine particle.

The following examples and experimental example are merely intended toillustrate the present invention in further detail and should not beconstrued as defining the scope of the invention.

EXAMPLES Example 1

Tetraglycerol dipalmitate (300 mg; the number of ester bond: 2.0;manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., Japan) was heated at48° C. for melting, and was added with 7.2 mg of a freeze-dried powderyinterferon-α. A part of the molten mixture was sucked up into a needleof 11 G by use of a syringe, cooled at room temperature and the chargedwas extruded from the needle to give a cylindrical matrix pharmaceuticalpreparation (1 mm in diameter, 10 mm in length, about 10 mg in weight).

Example 2

Tetraglycerol distearate (300 mg; the number of ester bonds: 2.0;manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., Japan) was heated at58° C. for melting, and to the molten was added 7.2 mg of a freeze-driedpowder of interferon-α. A portion of the molten mixture was sucked upinto a needle of 11 G by use of a syringe and was cooled at roomtemperature. The charged was extruded to give a cylindrical matrixpharmaceutical preparation (1 mm in diameter, 10 mm in length, about 10mg in weight).

Example 3

A molten mixture of tetraglycerol dipalmitate and the freeze-driedpowdery interferon-α was prepared in the same manner as in Example 1.The molten mixture was sucked up into a 1 ml-syringe (Terumo Co., Ltd.,Japan), and, with maintaining the temperature at 50° C., the matrix wassprayed or atomized with an air gun (Hakuko Co., Ltd., Japan) withextruding from a needle of 27 G (Terumo Co., Ltd., Japan) to givemicrospheres. The microspheres were passed through a sieve (16 mesh) toremove granular products having a diameter of 1 mm or more.

Example 4

After heated at 48° C. for melting, the molten tetraglycerol dipalmitate(300 mg; Sakamoto Yakuhin Kogyo Co., Ltd., Japan) was added with 1.5 mgof a freeze-dried powder of interleukin-2. A portion of the moltenmixture was sucked up to a needle of 11 G with a syringe, cooled at roomtemperature and extruded the charged from the needle to obtain acylindrical matrix pharmaceutical preparation having a diameter of 1 mm,a length of 20 mm and a weight of about 20 mg.

Example 5

Tetraglycerol dipalmitate (300 mg; Sakamoto Yakuhin Kogyo Co., Ltd.,Japan) was heated at 48° C. for melting, and to the molten was added 1.5mg of a freeze-dried powder of insulin. The molten mixture was sucked upinto a needle of 11 G by use of a syringe and cooled at roomtemperature. The charged was extruded from the needle to give acylindrical matrix pharmaceutical preparation (1 mm in diameter, 20 mmin length, about 20 mg in weight).

Comparative Example 1

A cylindrical matrix pharmaceutical preparation (1 mm in diameter, 10 mmin length, about 10 mg in weight) was obtained in the same manner as inExample 1 except for using glycerol monopalmitate (the number of esterbond: 1.0; Riken Vitamin Co., Ltd., Japan) instead of tetraglyceroldipalmitate.

Comparative Example 2

The procedures of Example 1 was followed by using diglycerolmonopalmitate (the number of ester bond: 1.0; Sakamoto Yakuhin KogyoCo., Ltd., Japan) instead of tetraglycerol dipalmitate to give acylindrical matrix pharmaceutical preparation having a diameter of 1 mm,a length of 10 mm and a weight of about 10 mg.

Comparative Example 3

A cylindrical pharmaceutical preparation (1 mm in diameter, 10 mm inlength, about 10 mg in weight) was prepared in the same manner as inExample 2 except for using glycerol monostearate (the number of esterbond: 1.0; Takeda Chemical Industries, Ltd., Japan) instead oftetraglycerol distearate.

Comparative Example 4

The procedure of Example 2 was repeated except for using diglycerolmonostearate (the number of ester bond: 1.0; manufactured by SakamotoYakuhin Kogyo Co., Ltd., Japan) in place of tetraglycerol distearate toobtain a cylindrical matrix pharmaceutical preparation having a diameterof 1 mm, a length of 10 mm and a weight of about 10 mg.

Comparative Example 5

A cylindrical pharmaceutical preparation (1 mm in diameter, 10 mm inlength and about 10 mg in weight) was prepared by the same procedure asin Example 2 except for using tetraglycerol monostearate (the number ofester bond: 1.0; Sakamoto Yakuhin Kogyo Co., Ltd., Japan) instead oftetraglycerol distearate.

Comparative Example 6

Using tetraglycerol tristearate (the number of ester bond: 3.0;manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., Japan) instead oftetraglycerol distearate, the procedures of Example 2 was followed togive a cylindrical pharmaceutical preparation (1 mm in diameter, 10 mmin length, about 10 mg in weight).

Example 6

A cylindrical pharmaceutical preparation (1 mm in diameter, 10 mm inlength, about 10 mg in weight) was prepared in the same manner as inExample 2 except for using tetraglycerol dimyristate (the number ofester bond: 2.0; Sakamoto Yakuhin Kogyo Co., Ltd., Japan) instead oftetraglycerol dipalmitate.

Experimental Example

The matrix pharmaceutical preparations obtained in Examples 1 and 2 andComparative Examples 1 to 6 were respectively administered to a maleJCL-SD rat (aged: 6 weeks) subcutaneously in the back in a dose of 10 mgby using a needle of 11 G with a syringe. Each cylindrical matrixpharmaceutical preparation contains 4×10⁷ International Unit (IU) ofinterferon-α.

As a control run, an aqueous solution containing 4×10⁷ IU ofinterferon-α was used.

After administration, 0.6 ml of blood was corrected from the tail veinwith the lapse of time to obtain serum samples. The serum samples weretaken respectively from three rats, and the concentration ofinterferon-α in each serum sample was determined by sandwich ELISA usingtwo species of anti-interferon-α antibodies, and the average value wascalculated. As the unit of standard interferon-α, Canferon-TM (TakedaChemical Industries, Ltd., Japan) was employed. The average values ofinterferon-α concentration in the serums with the passage of time afteradministration are set forth in Tables 1 and 2.

In Tables 1 and 2, the term "ND" means "not detectable".

                  TABLE 1                                                         ______________________________________                                        Time course after                                                                        Interferon Concentration in Serum (IU/ml)                          administration             Comp.  Comp. Comp.                                 (hr)       Ex. 1   Ex. 2   Ex. 1  Ex. 2 Ex. 3                                 ______________________________________                                        0.25       --      --      --     --    --                                    0.5        --      --      --     --    --                                    1.0        2086.4  2717.9  7544.1  5712.4                                                                             7790.5                                2.0        2394.1  4366.2  10692.8                                                                              13973.0                                                                             15576.8                               4.0        3753.5  3088.6  7021.8 12734.9                                                                             10122.6                               6.0        3380.1  2233.9  7555.4 15510.4                                                                             8134.6                                8.0        --      --      --     --    --                                    24.0       1651.3  1235.0  1666.8  3312.3                                                                             2586.5                                48.0       1196.4  810.3    315.0  1374.4                                                                              664.2                                78.0        913.7  421.1   --      597.1                                                                               205.5                                102.0      --      --       12.5  --    --                                    120.0       636.3  365.5   ND       60.5                                                                               42.6                                 144.0       509.4  184.7            41.8                                                                               10.8                                 168.0       629.0  304.0          ND    ND                                    192.0       568.1  777.4                                                      216.0       243.0  612.5                                                      288.0       11.8    43.4                                                      ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Time course after                                                                         Interferon Concentration in Serum (IU/ml)                         administration                                                                            Comp.    Comp.    Comp.                                           (hr)        Ex. 4    Ex. 5    Ex. 6  Control                                  ______________________________________                                        0.25        --       --       --     29991.7                                  0.5         --       --       --     44498.1                                  1.0         12288.5   6521.3  2058.2 52899.6                                  2.0         19530.8  14726.3  959.7  51446.0                                  4.0         10826.0  18105.3  582.6  17055.2                                  6.0          8680.0  17533.5  585.8   3770.4                                  8.0         --       --       --      1041.8                                  24.0         1932.5   2605.2   58.8   117.7                                   48.0         492.0     99.5    38.9  ND                                       78.0        --         43.3    11.3                                           120.0         43.3   ND       ND                                              144.0       ND                                                                168.0                                                                         192.0                                                                         216.0                                                                         288.0                                                                         ______________________________________                                    

As apparent from Tables 1 and 2, the pharmaceutical preparations ofExample 1 and Example 2 respectively obtained by using tetraglyceroldipalmitate and tetraglycerol distearate among polyglycerol higher fattyacid esters can sustainedly release interferon-α for one week or more,and the releasing period of interferon-α is longer than thepharmaceutical preparations of Comparative Examples by a factor of 2 ormore.

What is claimed is:
 1. A sustained releasable parenteral pharmaceuticalpreparation in cylindrical or columnar form which comprises a matrixcontaining an interferon-α and a polyglycerol diester of stearic acid orpalmitic acid, wherein said polyglycerol has an average polymerizationdegree of
 4. 2. A sustained releasable parenteral pharmaceuticalpreparation according to claim 1, wherein said interferon-α is dispersedin said diester.
 3. A sustained releasable parenteral pharmaceuticalpreparation according to claim 1, wherein said matrix is an injectablesolid for implantation.
 4. A method of producing a sustained releasableparenteral pharmaceutical preparation, which method comprises mixing aninterferon-α with a molten or softened polyglycerol diester of stearicacid or palmitic acid and molding the molten mixture into a cylindricalor columnar form, wherein said polyglycerol has an averagepolymerization degree of
 4. 5. A method of producing a sustainedreleasable parenteral pharmaceutical preparation according to claim 4,wherein the interferon-α is in a dried powdery form and is mixed withthe molten or softened diester.